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Abstract

The title potential anti­bacterial compound, C14H12N2O4·H2O, is a Schiff base which has an intra­molecular O—HN hydrogen bond and crystallizes with one uncoordinated water mol­ecule, which links three symmetry-related mol­ecules through two O—HO and one N—HO hydrogen bond. In the crystal structure, further inter­molecular O—HO hydrogen bonds link symmetry-related mol­ecules, forming layers parallel to the bc plane.

The molecular structure of the title compound (Fig. 1) is a Schiff base, which
has an intramolecular O1—H1···N1 hydrogen bond (Table 1), and crystallizes
as a water solvate. In the crystal structure the water molecule links three
symmetry related molecules through two donnor O—H···O hydrogen bonds and one
acceptor N—H···O hydrogen bond (Table 1). Together with two further
intermolecular O—H···O hydrogen bonds, layers parallel to the bc
plane are formed (Fig. 2).

Experimental

Salicylaldehyde and 3,5-dihydroxybenzoic acid hydrazide were purchased from
Aldrich and were used without further purification. Salicylaldehyde (0.1 mmol,
12.2 mg) and 3,5-dihydroxybenzoic acid hydrazide (0.1 mmol, 16.8 mg) were
mixed in a methanol solution (10 cm3). The mixture was stirred at reflux for
30 min and cooled to room temperature. After keeping the solution in air for a
few days, yellow block-shaped crystals appeard at the bottom of the vessel.

Refinement

The NH H-atom, H2A, and the water H-atoms were located from difference Fourier
maps and were refined with the N–H, O–H and H···H distances restrained to
0.90 (1), 0.85 (1) and 1.37 (2) Å, respectively. The remaining H-atoms were
placed in calculated positions and treated as riding atoms; C–H = 0.93 Å
with Uiso(H) = 1.2Ueq(C), and O–H = 0.82 Å with
Uiso(H) = 1.5Ueq(O).

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell e.s.d.'s are taken
into account individually in the estimation of e.s.d.'s in distances, angles
and torsion angles; correlations between e.s.d.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s.
planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor
wR and goodness of fit S are based on F2, conventional
R-factors R are based on F, with F set to zero for
negative F2. The threshold expression of F2 >
σ(F2) is used only for calculating R-factors(gt) etc.
and is not relevant to the choice of reflections for refinement.
R-factors based on F2 are statistically about twice as large
as those based on F, and R- factors based on ALL data will be
even larger.